Transfer of fluid from one vessel to another is an essential step in an extremely large number of operations both in commerce and in the laboratory. Pumps of a wide variety of types have been devised for carrying out the step at an appropriate rate, but, in general, the achievable precision desired for the transfer has not been completely satisfactory. Various valveless positive displacement pump systems have been developed to provide precision pumping, but such systems have not been completely suitable for automatic and random access. More specifically, it has not been possible to draw fluid automatically from a selected vessel and transfer the fluid in selected quantities to another selected vessel. Particularly, it has not been possible to carry out automatic transfer from one selected vessel to another selected vessel where a plurality of vessels are connected with the system and to carry out the transfer at low cost. Systems permitting choices between fluid sources lose precision or waste significant amounts of fluids they are mixing.
A particularly important case is the testing of blood samples which may be necessary in the office of a physician, at the bedside of a patient in a hospital or in the laboratory of a hospital where blood tests are carried out on a large scale for a number of patients. The number of blood tests, in particular, being carried out on a routine basis in hospitals is still expanding. Consequently, it has become necessary to devote a substantial fraction of the labor available in a hospital to this task. Also, the number of tests carried out is so large that there is serious danger of an intolerable increase in errors.
The physician practicing by himself illustrates the need for a relatively simple system which can carry out tests on blood or other fluids automatically and rapidly, so that the physician need not wait for the return of a report from an outside laboratory. In general, the report cannot be received quickly enough so that the patient can remain in the doctor's office. It would be highly desirable to have available a device which would carry out the required tests on the physician's premises so that the test results would become available in a few minutes, and generally, without the need for a technician to carry out the tests. As another example, hospitals now routinely take blood samples from each patient on admission and carry out a number of routine tests as well as any special tests which may be specified by a physician. The staff required to carry out such tests as the laboratories are now organized can be quite substantial. Again, it would be advantageous if routine tests, at least, could be carried out automatically and, of course, even more advantageous if the special tests could be carried out automatically. Another advantage would be the selection and improved availability of tests with limited staff and resources.
The present invention is designed to provide precision pumping as to quantity, choice among vessels from which fluid is to be drawn, choice among vessels to which fluid is to be transferred and with minimal waste. It is also intended to significantly improve the cost-effectiveness of various kinds of devices requiring precision and selectivity in fluid transfer by reducing the requirements for electromechanical subsystem components. The system can be placed under the control of a microprocessor or microcomputer for completely automatic transfer of fluid. The interconnections between inlet and outlet ports, in combination with computer programmed fluid pumping, can perform complex sequences of fluid processing.